Light receiving or emitting semiconductor apparatus

ABSTRACT

With a solar ball  10  serving as a light-receiving semiconductor apparatus, the outer surface of a spherical solar cell  1  is covered with a light-transmitting outer shell member  11 , and electrode members  14, 15  are connected to electrodes  6, 7  of the solar cell  1 . The outer shell member  11  comprises a capsule  12  produced by bonding together two halves, and a filler  13  that is packed inside this capsule and cured. A solar panel can be configured such that a plurality of the solar balls  10  are arrayed in a matrix and connected in parallel and in series, or a solar panel can be configured such that a multiplicity of spherical solar cells  1  are arrayed in a matrix and covered with a transparent outer shell member. A solar string in the form of a rod or cord can be configured such that a plurality of the solar cells  1  are arrayed in columns and connected in parallel, and then covered with a transparent outer shell member. Since the outer shell member  11  condenses light, the light-receiving area of the solar cell  1  can be expanded. Also discussed is a light-emitting semiconductor apparatus in which a spherical semiconductor device with a light-emitting function, rather than the solar cell  1 , is covered with an outer shell member.

TECHNICAL FIELD

The present invention relates to a light-receiving or light-emittingsemiconductor apparatus, and more particularly relates to an apparatusin which the outside of a spherical semiconductor device with alight-receiving or light-emitting function is covered with alight-transmitting outer shell member so as to improve the lightcondensation performance or light radiation performance. This can beused in various applications such as solar cells, lighting devices, anddisplay devices.

BACKGROUND OF THE INVENTION

Conventionally, research has been directed toward a technology forming apn junction via a diffusion layer on the surface of a small-diameterspherical semiconductor element composed of a p or n type semiconductor,connecting many of these spherical semiconductor elements in parallel toa common electrode, and putting to practical use for a solar cell orsemiconductor photocatalyst.

U.S. Pat. No. 3,998,659 discloses a solar cell configured such that a ptype diffusion layer is formed on the surface of an n type sphericalsemiconductor, the diffusion layers of many spherical semiconductors areconnected to a common membrane electrode (positive electrode), and the ntype cores of many spherical semiconductors are connected to a commonmembrane electrode (negative electrode).

U.S. Pat. No. 4,021,323 discloses a solar energy converter(semiconductor module) in which p type spherical semiconductor elementsand n type spherical semiconductor elements are disposed in series,these semiconductors are connected to a common film-like electrode, andthe diffusion layers of these semiconductor elements are brought intocontact with a common electrode in the electrolyte, so that theelectrolyte will undergo electrolysis when irradiated with sunlight.

With the modules featuring spherical cells disclosed in U.S. Pat. Nos.4,582,588 and 5,469,020, each spherical cell is attached by beingconnected to a common sheet-like electrode, so this configuration issuitable for the parallel connection of a plurality of cells, but notfor the serial connection.

Meanwhile, as discussed in U.S. Pat. Nos. 6,204,545 and 6,294,822, theinventor of the present invention has proposed a granularlight-receiving or light-emitting semiconductor device in which adiffusion layer, a pn junction, and a pair of electrodes are formed onspherical semiconductor elements composed of p type or n typesemiconductor, and in U.S. Pat. No. 6,204,545 the inventor has proposeda semiconductor module that is applicable to solar cells, photocatalystapparatuses used in the electrolysis of water, a variety of lightemitting devices, and color displays, and so forth. With thissemiconductor module, if any of the semiconductor device in any of theserial connection becomes open through malfunction, current stopsflowing to the serial circuit including that semiconductor element, theremaining properly-functioning semiconductor devices in the serialconnection also cease functioning, and the output of the semiconductormodule decreases.

In view of this, the inventors have come up with a serial/parallelconnection structure in which a plurality of semiconductor cells aredisposed in a matrix, the semiconductor cells in each column areconnected in series, and the semiconductor cells in each row areconnected in parallel, and have filed several international patentapplications.

However, the semiconductor module in U.S. Pat. No. 6,204,545 employs astructure in which the electrodes of the semiconductor cells areconnected so that a plurality of semiconductor cells are connected inseries, and these serial connections are arrayed in a plurality ofplanar rows, and the pair of electrodes of each semiconductor cell isextremely small, so when the above-mentioned serial/parallel connectionstructure is employed, manufacture becomes complicated, it is difficultto produce a large semiconductor module, and the cost of manufacturing asemiconductor module rises.

As discussed above, the spherical semiconductor device proposed by theinventor has a small diameter of only about 1 to 3 mm, so when it isapplied in a solar panel or light emitting panel, for instance, a largenumber of these spherical semiconductor devices end up being disposedjust a few millimeters apart in a matrix. Because so many of thespherical semiconductor devices are required in this case, manufacturingexpense become higher. With a solar panel, it is possible to reduce thenumber of spherical semiconductor devices needed by additionallyproviding the spherical semiconductor devices in each column with acylindrical condensing lens, so that the spacing between columns isincreased. However, the position and orientation of the condensing lensmust be varied according to the incident direction of the sunlight, andalso a complex and expensive mechanism is needed to movably support andcontrol the orientation of the condensing lens, so this situation isimpractical.

Meanwhile, in the case of a light emitting panel used for lighting ordisplay, the light emitted from the small-diameter sphericalsemiconductor device tends to be excessively bright, and it is difficultto construct a light emitting panel that emits soft light of the properbrightness.

The object of the present invention is to provide a light-receivingsemiconductor apparatus with improved condensing function that condenseslight in a light-receiving spherical semiconductor device; alight-receiving semiconductor apparatus with improved condensingfunction and which is less apt to be affected by the malfunction of someof the spherical semiconductor devices when a plurality of sphericalsemiconductor device are disposed in a plurality of rows and a pluralityof columns; a light-receiving semiconductor apparatus with improvedcondensing function and in which a plurality of spherical semiconductordevices disposed in one or more columns are connected in parallel ineach column unit; and a light-emitting semiconductor apparatus withimproved light diffusion function that diffuses the light emitted from alight-emitting spherical semiconductor device.

DISCLOSURE OF THE INVENTION

The light-receiving or light-emitting semiconductor apparatus accordingto the present invention comprises at least one spherical semiconductordevice with a light-receiving function or a light-emitting function,wherein the spherical semiconductor device comprises a p or n typesemiconductor crystal with a spherical outer shape, a pn junction formedsubstantially spherically on the surface layer portion of thesemiconductor crystal, and a pair of electrodes connected to both endsof the pn junction and located on either side with interposing thecenter of curvature of the pn junction therebetween, and there isprovided an outer shell member constituted so as to cover an outside ofthe spherical semiconductor device with a light-transmitting wallcomponent whose thickness is at least ¼ the diameter of the sphericalsemiconductor device, and so that the outer surface of this outer shellmember forms a sphere or partial sphere.

When this semiconductor apparatus is a light-receiving semiconductorapparatus, external light is incident on the outer surface of the outershell member, most of this incident light is refracted at the surfaceand enters the interior of the outer shell member, eventually reachingthe spherical semiconductor device and generating photovoltaic power.Since the outer surface of the outer shell member is spherical orpartially spherical, the incident light reaches the sphericalsemiconductor device and generates photovoltaic power even if thedirection of incidence varies.

Because the outer shell member covers the outside of the sphericalsemiconductor device with a light-transmitting wall component whosethickness is at least ¼ the diameter of the spherical semiconductordevice, the outer shell member exhibits a condensing function, there isan increase in the light-receiving surface area per sphericalsemiconductor device, and more light reaches each sphericalsemiconductor device.

When this semiconductor apparatus is a light-emitting semiconductorapparatus, the light generated from the substantially spherical pnjunction is radiated in substantially all directions, and is radiated tothe outside from the spherical or partial-spherical outer surface of theouter shell member. Because the outer shell member covers the outside ofthe spherical semiconductor device with a light-transmitting wallcomponent whose thickness is at least ¼ the diameter of the sphericalsemiconductor device, the outer shell member exhibits a light diffusionfunction, the size of the light emission source is increased, thebrightness of the light radiated from the emission source is lessened,and a softer light is radiated to the outside.

The following constitutions can also be employed as desired.

(a) The outer surface of the outer shell member comprises a sphericallight-transmitting capsule forming the outer surface portion of theouter shell member, and a filler composed of a light-transmittingsynthetic resin that is packed into this capsule and cured.

(b) Multiplicity of microscopic light scattering surfaces are formed onthe outer surface of the outer shell member.

(c) There is provided a pair of electrode members respectively connectedto the pair of electrodes of the spherical semiconductor device andextending through the outer shell member at least to the outer surfaceof the outer shell member.

(d) A plurality of spherical semiconductor devices, each having an outersurface covered with the outer shell member that forms a sphere, arearrayed in a matrix of a plurality of rows and a plurality of columns,and there are provided a serial connection mechanism for electricallyconnecting in series the plurality of spherical semiconductor devices ineach row or column, and a parallel connection mechanism for electricallyconnecting in parallel the plurality of spherical semiconductor devicesin each column or row.

(e) A plurality of spherical semiconductor devices are arrayed in amatrix of a plurality of rows and a plurality of columns, there isprovided a conduction connection mechanism for electrically connectingin parallel the plurality of spherical semiconductor devices in each rowor column, and the outer shell member comprises a plurality ofsubstantially spherical outer shell components covering each of theplurality of spherical semiconductor devices, and a flat componentformed integrally with the plurality of outer shell components.

(f) The conduction connection mechanism comprises a plurality ofconductor wires, which are part of a network structure constituted bythe plurality of conductor wires and a plurality of insulator wires laidout perpendicularly to these conductor wires.

(g) Another light-receiving or light-emitting semiconductor apparatus ofthe present invention comprises a plurality of spherical semiconductordevices with a light-receiving function or a light-emitting function,wherein each of the spherical semiconductor devices comprises a p or ntype semiconductor crystal with a spherical outer shape, a pn junctionformed substantially spherically on the surface layer portion of thesemiconductor crystal, and a pair of electrodes connected to both endsof the pn junction and located on either side with interposing thecenter of curvature of the pn junction therebetween, there is provided aconduction connection mechanism for electrically connecting in parallelthe plurality of spherical semiconductor devices, with the plurality ofspherical semiconductor devices being disposed in a single column, andthere is provided an outer shell member that covers an outside of theplurality of spherical semiconductor devices with a light-transmittingwall component whose thickness is at least ¼ the diameter of thespherical semiconductor devices, and that has a cylindrical outersurface.

(h) Still another light-receiving or light-emitting semiconductorapparatus comprises a plurality of spherical semiconductor devices witha light-receiving function or a light-emitting function, wherein each ofthe spherical semiconductor devices comprises a p or n typesemiconductor crystal with a spherical outer shape, a pn junction formedsubstantially spherically on the surface layer portion of thesemiconductor crystal, and a pair of electrodes connected to both endsof the pn junction and located on either side with interposing thecenter of curvature of the pn junction therebetween, a plurality ofspherical semiconductor devices are disposed in a plurality of columns,there is provided a conduction connection mechanism for electricallyconnecting in parallel a plurality of spherical semiconductor devices ofeach of these columns in column units, and there is provided a outershell member that covers in common the outside of the plurality ofspherical semiconductor devices with a light-transmitting wall componentwhose thickness is at least approximately equal to the diameter of thespherical semiconductor devices, and that has a plurality of cylindersof substantially cylindrical shape that cover each of the plurality ofcolumns of spherical semiconductor devices.

(i) The spherical semiconductor devices have a photovoltaic powergenerator that includes the pn junction.

(j) The spherical semiconductor devices have an electro-opticalconverter that includes the pn junction.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate embodiments of the present invention.

FIG. 1 is an enlarged cross section of a spherical semiconductor device;

FIG. 2 is an enlarged cross section of a solar ball;

FIG. 3 is an enlarged side view of the solar ball in FIG. 2;

FIG. 4 is a detail enlarged cross section of the outer shell member;

FIG. 5 is an enlarged cross section illustrating the state when theinside of a capsule has been filled with a liquid, transparent,synthetic resin;

FIGS. 6, 7 are each an enlarged cross section of a solar ball, andillustrating the behavior of light during its receipt;

FIG. 8 is a detail enlarged plan view of a solar panel in which thesolar balls of FIG. 2 have been arrayed in a plurality of rows and aplurality of columns;

FIG. 9 is an enlarged cross section along the IX—IX line in FIG. 8;

FIG. 10 is a circuit diagram of an equivalent circuit of the solar panelof FIG. 8;

FIG. 11 is an equivalent circuit partial diagram in which part of theequivalent circuit in FIG. 10 has been changed;

FIG. 12 is an enlarged cross section of the solar ball pertaining to amodification example;

FIG. 13 is an enlarged cross section of the mold used to form the solarball of FIG. 12, a spherical solar cell, and a pair of electrodemembers;

FIG. 14 is an enlarged cross section of the solar ball pertaining toanother modification example;

FIGS. 15 to 17 are diagrams related to the solar panel according toanother embodiment, with FIG. 15 being a detail enlarged plan view ofthe solar panel, FIG. 16 a cross section along the XVI—XVI line in FIG.15, and FIG. 17 a cross section along the XVII—XVII line in FIG. 15;

FIGS. 18 to 21 are diagrams, related to the solar panel and solar stringpertaining to another embodiment, with FIG. 18 being a plan view of thesolar panel, FIG. 19 a side view of the case, FIG. 20 an enlarged crosssection of the solar string, and FIG. 21 a cross section along theXXI—XXI line in FIG. 20;

FIG. 22 is a detail enlarged side view of the solar panel pertaining toa modification example; and

FIG. 23 is an enlarged cross section of a light emitting ball pertainingto another embodiment.

PREFERRED EMBODIMENT OF THE INVENTION

The most preferable embodiment of the present the invention will now bedescribed through reference to the drawings.

First, descriptions will be made on a spherical solar cell 1incorporated into a solar panel, which serves as a light-receivingsemiconductor apparatus. This solar cell 1 corresponds to a sphericalsemiconductor device.

FIG. 1 shows an enlarged cross section of a spherical solar cell 1. Thissolar cell 1 is made from a spherical crystal 2 with a diameter ofapproximately 0.6 to 2.0 mm, composed of a p type silicon monocrystalwith a resistivity of about 1 Ωm. A flat surface 3 with a diameter ofapproximately 0.6 mm is formed at the bottom of this spherical crystal2. On the surface portion of this spherical crystal 2 formed is an n+type diffusion layer 4 (approximately 0.4 to 0.5 μm thick) in whichphosphorus (P) has been diffused, and a pn junction 5 that issubstantially spherical in shape. The 0.6 mm diameter of the flatsurface 3 is the size when the spherical crystal 2 has a diameter of 2.0mm.

A pair of electrodes 6, 7 (positive electrode 6 and negative electrode7) are provided at the two ends, with interposing the center of thespherical crystal 2 (the center of curvature of the pn junction 5)therebetween. The positive electrode 6 is disposed on the flat surface 3and is connected to the spherical crystal 2, while the negativeelectrode 7 is connected to the n+ type diffusion layer 4. The entiresurface other than the positive electrode 6 and the negative electrode 7is covered with an antireflective film 8 (approximately 0.6 to 0.7 μmthick) composed of a SiO2 or TiO2 insulating film. The positiveelectrode 6 is formed by baking an aluminum paste, for example, and thenegative electrode 7 is formed by baking a silver paste.

A solar cell 1 such as this can be produced by first producing thespherical crystal 2 by the method proposed by the inventor in U.S. Pat.No. 6,204,545, and then forming the flat surface 3, the n+ typediffusion layer 4, the pair of electrodes 6, 7, and the antireflectivefilm 8. When the spherical crystal 2 is produced, a dropping tube with aheight of approximately 14 m is employed, grains of p type silicon (theraw material) are heated and melted inside the upper end of the droppingtube, and the material falls freely and solidifies while maintained in atrue spherical shape by the action of surface tension, thereby producingthe spherical crystals 2 in the form of substantially true spheres. Thespherical crystals 2 need not be formed with a dropping tube, and mayinstead be formed into spherical or substantially spherical crystals bymechanical grinding or another such method.

The flat surface 3 can be formed by mechanically grinding part of thespherical crystal 2. Forming this flat surface 3 makes the sphericalcrystal 2 less prone to rolling, allows it to be chucked with a vacuumchuck, and allows the positive electrode 6 to be distinguished from thenegative electrode 7. Next, when the n+ type diffusion layer 4 isformed, the flat surface 3 of the spherical crystal 2 and the portionaround the outer periphery of this flat are masked with SiO2, andphosphorus (P) is diffused as a n type impurity into the surface of thespherical crystal 2 by a known method or the method disclosed in theabove-mentioned publication. The pair of electrodes 6, 7 and theantireflective film 8 can also be formed by a known method or the methoddisclosed in the above-mentioned publication. This solar cell 1 has anphoto-electric conversion function, and generates a photovoltaic powerof 0.5 to 0.6 V when irradiated with sunlight.

Next, descriptions will be made on the solar ball 10, as a semiconductorapparatus structured such that the outside of the above-mentioned solarcell 1 is covered with the light-transmitting outer shell member 11.

FIG. 2 shows an enlarged cross section of the solar ball 10. This solarball 10 comprises the solar cell 1 located in the center, thelight-transmitting outer shell member 11 that covers the outside of thissolar cell 1 with a light-transmitting wall component whose thickness isat least ¼ the diameter of the solar cell 1, and a pair of electrodemembers 14, 15. This outer shell member 11 serves to increase the amountof light introduced into the solar cell 1, and comprises a capsule 12 inthe form of a light-transmitting spherical shell, and alight-transmitting filler 13 that fills this capsule 12.

The capsule 12 is made of a transparent, insulating synthetic resin(such as a polycarbonate, acrylic, polyarylate, methacrylic, silicone,or polyester) or transparent glass, and is 0.2 to 1.0 mm in thickness,for example. In order for the interior of the capsule 12 to accommodatethe solar cell 1, the capsule 12 is formed as a spherical capsule bybonding together a pair of hemispherical capsule segments 12 a.

In order for as much as possible of the light incident on this capsule12 from the outside to be guided into the capsule 12, a multiplicity ofmicroscopic irregularities 12 b in the form of pointed pyramids as shownin FIG. 4 are formed on the outer surface of the capsule 12 as lightscattering surfaces. These microscopic irregularities 12 b may bepointed pyramids as shown in the drawing, or may consist of convexcurved surfaces with a small radius of curvature.

The filler 13 is provided by filling the inside of the capsule 12 with atransparent, insulating synthetic resin (such as a filler whose maincomponent is a methacrylic resin or a silicone resin) in the form of aliquid, and then curing the filler by heating or UV irradiation. Thethickness of the light-transmitting wall component of the outer shellmember 11 (the thickness from the surface of the capsule 12 to the solarcell 1) is preferably at least ¼ the diameter of the solar cell 1. Ifthe thickness of the light-transmitting wall component is less than ¼the above-mentioned diameter, almost no function of increasing thequantity of light will be obtained. If the light-transmitting wallcomponent of the outer shell member 11 is too thick, however, there willbe a greater portion that does not contribute to increase the amount oflight guided to the solar cell 1, so the thickness of thelight-transmitting wall component of the outer shell member 11 ispreferably about ¼ to 5 times the diameter of the solar cell 1.

In order to reduce the reflection of light at the surface of the capsule12, it is preferable for the refractive index of the material that makesup the capsule 12 to be as near to 1.0 as possible, and for therefractive index of the synthetic resin material that makes up thefiller 13 to be as large as possible. The majority of the outer shellmember 11 may be made up of a capsule having a plurality of layers, withthe optical refractive index decreasing in stages from the centeroutward.

The pair of electrode members 14, 15 are preferably made up of a metalwith excellent conductivity (such as copper, silver, or nickel). Theelectrode member 14 passes through a hole formed in the outer shellmember 11, the distal end of the electrode member 14 is connected withsolder or an electroconductive adhesive to the positive electrode 6 ofthe solar cell 1, and the other end of the electrode member 14 protrudesby a specific length outward from the outer surface of the capsule 12.The electrode member 15 passes through a hole formed in the outer shellmember 11, the distal end of the electrode member 15 is connected withsolder or an electroconductive adhesive to the negative electrode 7 ofthe solar cell 1, and the other end of the electrode member 15 protrudesby a specific length outward from the outer surface of the capsule 12.

When the solar ball 10 is produced, the solar cell 1, the pair ofhemispherical capsule segments 12 a, the pair of electrode members 14,15, and the liquid raw material of the filler 13 are readied, the pairof electrode members 14, 15 are first attached to the spherical solarcell 1, and this solar cell 1 with its attached pair of electrodemembers 14, 15 is housed in the pair of hemispherical capsule segments12 a, after which the capsule segments 12 a are put together to form asphere, and the contact surfaces around the circumference are joinedwith an adhesive to create a spherical capsule 12.

Next, as shown in FIG. 5, the electrode member 14 is made to protrude tothe outside from one of the holes in the capsule 12, the electrodemember 15 is set in place away from and to the inside of the other holein the capsule 12, and in this state the inside of the capsule 12 isfilled with the liquid filler raw material as indicated by the arrows.The solar cell 1 is then positioned at the center inside the capsule 12,and UV irradiation is then performed, for example, which cures the rawmaterial to create the filler 13.

The action of this solar ball 10 will now be described. As shown in FIG.6, when sunlight is incident, for instance, because the outer shellmember 11 is spherical and the light incident on the outer surfacethereof is guided to the center by refraction, the amount of lightguided to the spherical solar cell 1 is markedly increased by thecondensing action of the outer shell member 11. Furthermore, reflectionat the boundary between the capsule 12 and the filler 13 creates anaction whereby the light is confined in the interior, so the amount oflight received by the spherical solar cell 1 is increased.

The amount of light received by the spherical solar cell 1 can befurther increased by forming an antireflective film on the surface ofthe lower half of the capsule 12 of the solar ball 10 in FIG. 6. FIG. 7shows the state when the sunlight is slanted to the west, but since theouter surface of the outer shell member 11 is spherical, the conditionsunder which the light is received are substantially the same as in FIG.6.

Next, descriptions will be made on a solar panel 20 in which many of thesolar balls 10 are incorporated. As shown in FIGS. 8 and 9, this solarpanel 20 comprises a base panel 21 made of a light-transmitting,insulating, synthetic resin, a plurality of solar balls 10 disposed in aplurality of rows and a plurality of columns on this base panel 21, aserial connection mechanism 22 a for the serial connection of thesesolar balls 10, a parallel connection mechanism 22 b for the parallelconnection of each row of solar balls 10, a light-transmitting,synthetic resin surface cover layer 23 that covers the top surface ofthe base panel 21, the serial connection mechanism 22 a, and theparallel connection mechanism 22 b, and so forth. The base panel 21 ismade of a transparent synthetic resin (such as a polycarbonate, acrylic,polyarylate, methacrylic, silicone, or polyester) or transparent glass,having a size of 30 cm×30 cm and a thickness of 3.0 to 5.0 mm, forexample. Substantially hemispherical recesses 24 for situating the solarballs 10 are formed in a matrix of a plurality of rows and a pluralityof columns at a specific spacing on the top of this base panel 21. Asshown in FIG. 8, the serial connection mechanism 22 a and the parallelconnection mechanism 22 b are constituted by a plurality of strips ofconductive film 25 formed parallel to the planar portion on the top ofthe base panel 21. These conductive film strips 25 are composed of atransparent, conductive, synthetic resin or a metal film (such as copperor nickel).

The electrode members 14, 15 of the plurality of solar balls 10 areoriented in parallel with their polarity aligned, and these solar balls10 are mounted in the plurality of rows and plurality of columns of therecesses 24. For example, the electrode member 14 on the positiveelectrode 6 side faces upward in FIG. 8, the electrode member 15 on thenegative electrode 7 side faces downward as viewed in FIG. 8, and theelectrode members 14, 15 are connected with solder or anelectroconductive adhesive to the corresponding conductive film strips25.

In other words, the plurality of solar balls 10 in each row areconnected in parallel by the conductive film strips 25 on both sides,and the plurality of solar balls 10 in each column are connected inseries via a plurality of the conductive film strips 25. A positiveelectrode terminal 26 (external lead) composed of a thin metal sheetwhich is connected to the conductive film strip 25 at the end on thecurrent output side, and a negative electrode terminal 27 (see FIG. 10)that is the same as discussed above is connected to the conductive filmstrip 25 on the opposite end from the conductive film strip 25 on thisend on the current output side.

The surface cover layer 23, which is composed of a light-transmitting,insulating synthetic resin, is formed over the upper surface of the basepanel 21, except for the part where the plurality of solar balls 10 arepresent. The upper half of the plurality of solar balls 10 protrudesbeyond the surface cover layer 23. A metal reflective film 28 is formedon the lower surface of the base panel 21 in order to prevent light frombeing transmitted to the underside of the solar panel 20. The reflectivefilm 28 is not essential, though, and may be omitted.

With this solar panel 20, the light received by the solar cell 1 iscondensed by the outer shell member 11 provided to each of the solarballs 10, so each solar cell 1 receives light over a greater area.Accordingly, each solar cell 1 generates more electricity, theutilization factor of the solar cell 1 is higher, and the solar cells 1can be arrayed at a greater pitch, which means that fewer solar cells 1are required. Since the upper surface of each of the solar balls 10 ishemispherical in the solar panel 20, light coming from all directions inthree-dimensional space can be guided to the spherical solar cells 1, sothere is no decrease in power generating performance if the direction oflight incidence should change.

If we assume that the solar balls 10 are arrayed in ten rows and fivecolumns in the solar panel 20, for instance, then an equivalent circuitof this solar panel 20 is as shown in FIG. 10, and the current generatedas photovoltaic power by the 50 solar balls 10 flows from the positiveelectrode terminal 26 to an external circuit.

Since the solar balls 10 in each row are connected in parallel, and thesolar balls 10 in each column are connected in series with this solarpanel 20, even if there should be a decrease in or a halt to functiondue to shade or malfunctioning of any of the solar balls 10, just thephotovoltaic power from these solar balls 10 will decrease or come to astop, and the output of the properly functioning solar balls 10 will bediverted through the other solar balls 10 connected in parallel, sothere will be almost no adverse effect resulting from a malfunction ordecrease in function of some of the solar cells 1, the result being thatthe solar panel 20 has excellent reliability and durability.

As shown in FIG. 11, it is preferable here to provide an anti-reversecurrent diode 29 near the negative electrode terminal 27. Specifically,when this solar panel 20 is connected to a battery, there is the dangerthat the solar panel 20 will be damaged if current reverses from thebattery while the solar panel 20 is shut down at night, so the flow ofreverse current is prevented by the anti-reverse current diode 29.

Next, a modification of the solar ball 10 will be described.

With the solar ball 10A shown in FIG. 12, an outer shell member 11Acomposed of a kind of filler is provided instead of the outer shellmember 11 discussed above. When this solar ball 10A is produced, asshown in FIG. 13, the pair of electrode members 14, 15 connected to thesolar cell 1 are placed in molds 16, 17, a light-transmitting,insulating, molten synthetic resin (such as a polycarbonate or acrylic)is cast into a cavity 18 within the molds 16, 17 and cured, whichproduces the solar ball 10A. It is preferable, though, for microscopiclight-scattering irregularities similar to the those in FIG. 4 to beformed on the outer surface of the solar ball 10A.

Next, another modification of the solar ball will be described.

With the solar ball 10B shown in FIG. 14, an outer shell member 11B isformed in the shape of a partial sphere such that approximately thelower third of the sphere is removed. The upper surface of the outershell member 11B is formed as a partial sphere, while the bottom of theouter shell member 11B is formed flat. The outer shell member 11B ismade up of a light-transmitting, insulating synthetic resin material.The solar cell 1 is located at the center of the sphere of the outershell member 11B, the negative electrode 7 and the positive electrode 6are oriented up and down, respectively, the positive electrode 6protrudes slightly from the bottom, and an electrode member 15Bconnected to the negative electrode 7 passes through the outer shellmember 11B and protrudes from the outer surface thereof. A metalreflective film 19 is formed on the bottom of the outer shell member11B, divided by the positive electrode 6.

The performance of this solar ball 10B in terms of receiving lightincident from above is comparable to that of the solar balls 10, 10A,and since the reflective film 19 is formed, less light is transmitted tobelow. The material expense is lower because less material is needed forthe outer shell member 11B.

Other Embodiment 1 (See FIGS. 15 to 17)

Next, descriptions will be made on another embodiment of a solar panel50 in which many of the solar cells 1 are incorporated. This solar panel50 corresponds to a semiconductor apparatus. With the solar panel 50shown in FIGS. 15 to 17, a plurality of spherical solar cells 1 arearrayed in a matrix of a plurality of rows and a plurality of columns, aconduction connection mechanism is provided for electrically connectingin parallel the plurality of solar cells 1 in each row or column, andthere is provided an outer shell member 51 comprising a plurality ofsubstantially spherical outer shell components 52 that cover theplurality of solar cells 1, and a flat component 53 formed integrallywith the plurality of outer shell components 52.

The solar cells 1 are located at the center of the outer shellcomponents 52, the outer shell components 52 cover the outer surface ofthe solar cells 1 with a light-transmitting wall component, and each ofthe outer shell components 52 is formed integrally with its adjacentouter shell components 52. The thickness of the light-transmitting wallcomponent of the outer shell components 52 is preferably at least ¼ thediameter of the solar cell 1. The outer shell components 52 have thesame function as the outer shell member 11 of the solar ball 10.

The conduction connection mechanism comprises a plurality of conductionwires 54, which are part of a network structure 56 made up of theseconduction wires 54 and a plurality of insulator wires 55 disposedperpendicular to the conduction wires 54. In this network structure 56,the pairs of conduction wires 54 along a column of solar cells 1 areprovided at a spacing equal to the diameter of the solar cells 1, andthe pairs of insulator wires 55 along a row of solar cells 1 areprovided at a spacing equal to the diameter of the solar cells 1.

When this solar panel 50 is produced, the first step is to ready aplurality of solar cells 1 and the network structure 56 whose outerperiphery is supported by a rectangular frame 57, and dispose theplurality of solar cells 1 on this network structure 56 as shown in FIG.15. The positive electrodes 6 of the solar cells 1 are installed facingto the left as viewed in FIG. 15, and the negative electrodes 7 to theright as viewed in FIG. 15. In this case, since the solar cells 1 can befitted into the squares of the network structure 56 and fixed, manysolar cells 1 can be simply and efficiently mounted on the networkstructure 56.

Next, the positive electrodes 6 of the solar cells 1 are connected bysolder or an electroconductive adhesive to the corresponding conductionwires 54, and the negative electrodes 7 of the solar cells 1 areconnected by solder or an electroconductive adhesive to thecorresponding conduction wires 54. The network structure 56 to whichthese many solar cells 1 have been mounted is then placed in a specificmold of an injection molding apparatus, a melt of a light-transmitting,insulating synthetic resin (such as a polycarbonate or acrylic) isinjected into the molding cavity of this mold, and the solar panel 50shown in FIGS. 15 to 17 is molded. After this molding, the moldedarticle is taken out of the mold, and the outer periphery of the networkstructure 56 is cut where indicated by the dashed lines 58 and separatedfrom the frame 57, resulting in the state shown in FIG. 15.

With this solar panel 50, the plurality of solar cells 1 in each columnare connected in parallel by a conduction connection mechanismconsisting of a pair of conduction wires 54, and the output voltage ofthe solar cells 1 in each column is 0.5 to 0.6 V. To raise the outputvoltage of the solar panel 50, a plurality of columns of solar cells 1can be connected in series via the conduction wires 54 protruding to theouter periphery, in which case the equivalent circuit of this solarpanel 50 will be the same as the circuit shown in FIG. 10. One or morediodes for preventing reverse current may be provided as shown in FIG.11.

Basically the same action is obtained with this solar panel 50 as withthe solar panel 20 described above. Also, because the structure isvertically symmetrical, so that light can be received equally from aboveand below, this configuration makes it possible to construct a solarpanel that is applied to window glass, or a solar panel that is used inplace of window glass. If only light incident from the top side is to bereceived by the solar panel 50, though, a reflective film may be formedby plating or another such method on the bottom side of the solar panel50.

Furthermore, with this solar panel 50, rather than first readying manyof the solar balls 10 and then assembling them into a panel, a panel isassembled from a multiplicity of solar cells 1 using the networkstructure 56, after which the solar panel 50 is created by injectionmolding, so production entails fewer steps and the cost of production isreduced. It is also possible for the outer shell member 51 to consist oftransparent glass.

Other Embodiment 2 (See FIGS. 18 to 21)

Next, descriptions will be made on a solar panel 60 in which many of thesolar cells 1 are incorporated into a solar string 61, and these areassembled into panel form. This solar string 61 corresponds to asemiconductor apparatus, and this solar panel 60 also corresponds to asemiconductor apparatus.

As shown in FIGS. 18 and 19, the solar panel 60 comprises a case 62 madeof a transparent synthetic resin, and five (for example) solar strings61 housed in this case 62. The case 62 consists of fiveintegrally-molded, substantially cylindrical string holders 63 capableof holding the solar strings 61, and a flange 64 is formed at the lowerend of each of the string holders 63. As shown in FIGS. 20, 21, thesolar strings 61 have a plurality of spherical solar cells 1 arranged ina column, a conduction connection mechanism 65 for connecting thesesolar cells 1 in parallel, and an outer shell member 66 that has acylindrical outer surface and covers all of the outside of the pluralityof solar cells 1 with a light-transmitting wall component whosethickness is at least ¼ the diameter of a solar cell 1.

The solar cells 1 are the same as those described in the aboveembodiments. A plurality of the solar cells 1 are disposed with theirdirection of conductivity aligned, with the positive electrodes 6 facingto the left in FIG. 20 and the negative electrodes 7 facing to the rightin FIG. 20, and so that there is a slight gap left between adjacentsolar cells 1. The conduction connection mechanism 65 is mainlyconstituted by a pair of slender, metal conduction wires 65 a, 65 b.These conduction wires 65 a, 65 b are made of, for example, copper,aluminum, nickel, a silver alloy, or a gold alloy. The positiveelectrodes 6 of a plurality of solar cells 1 are connected by solder oran electroconductive adhesive to the conduction wire 65 a, while thenegative electrodes 7 of a plurality of solar cells 1 are connected bysolder or an electroconductive adhesive to the conduction wire 65 b.These solar cells 1 and the conduction connection mechanism 65 arecovered by the transparent outer shell member 66. The outer shell member66 is made of a transparent, insulating synthetic resin (such as apolycarbonate, polyarylate, methacrylic, silicone, or polyester), butmay be made of a hard synthetic resin, or of a soft, flexible syntheticresin. One end of the conduction wires 65 a, 65 b protrudes by aspecific length from the outer shell member 66, and power can be takenoff to the outside from these protruding ends.

These solar strings 61 are formed in the same length as the case 62, andas shown in FIG. 18, five of the solar strings 61 are housed in the fivestring holders 63 of the case 62. The five solar strings 61 can beserially connected by connecting with external leads 67 as shown in FIG.18. In this case, if the photovoltaic power of the solar strings 61 isassumed to be about 0.6 V, then the solar panel 60 shown in FIG. 18 cangenerate a photovoltaic power of about 3.0 V.

With this solar panel 60, the outer surface of the outer shell member 66is cylindrical rather than spherical, but more or less just as with theouter shell member 11 discussed above, light coming from variousdirections is easily guided toward the spherical solar cells 1, whichincreases the amount of light received, so each solar cell 1 receiveslight over a greater area. The case 62 is not essential, and the fivesolar strings 61 may instead be aligned and bonded together, orsandwiched between a pair of transparent panels.

Additional description will be given at this point for another exampleof the usage of the solar strings 61. The solar strings 61 can also beused in configurations other than that of the solar panel 60. Forinstance, if the solar strings 61 are to be used as the power supply fora mobile electronic device, they can be incorporated into necklaces,broaches, wristbands, handbags, belts, hats, eyeglasses, or other suchpersonal accessories, or part of such accessories.

In this case, if the outer shell member 66 is made from a soft, flexiblesynthetic resin as needed, the result will be flexible solar strings 61.It is also possible for a plurality of the solar strings 61 to bearranged serially or in a linked form so that they are electricallyconnected in series.

With the solar strings 61, since a plurality of solar cells 1 areconnected in parallel, the voltage of the photovoltaic power of each ofthe solar strings 61 is substantially constant (0.5 to 0.6 V), andtherefore a photovoltaic power of about 3.0 V can be generated byconnecting five or six of the solar strings 61 in series, and aphotovoltaic power of the desired voltage can be generated by suitablyselecting the number of solar strings 61 to be serially connected.Furthermore, while only very little current is generated by eachindividual solar cell 1, a current corresponding to the number of solarcells 1 incorporated into the solar strings 61 can be generated,affording excellent versatility.

The structure of the solar strings 61 is not limited to what is shown inthe drawings, and may instead be, for example, a structure in which alarge spacing is set between the solar cells 1, and the outside of eachsolar cell 1 is covered with a spherical outer shell member or asubstantially spherical outer shell member. A structure such as anetwork in which solar strings are combined longitudinally and laterallymay also be employed.

As an example of a solar panel in which the solar strings 61 arealigned, as shown in FIG. 22, the outer shell members 66A (correspondingto cylindrical components) of a plurality of solar strings 61A can beintegrally structured to configure a solar panel 60A.

Next, various examples of modifying the above embodiments andmodifications will be described.

1) In the solar cell 1, a spherical crystal composed of an n typesilicon monocrystal may be employed in place of the spherical crystal 2composed of a p type silicon monocrystal, and a p type diffusion layermay be formed instead of the n type diffusion layer 4. In this case thepositive electrode 6 and the negative electrode 7 are reversed.

Also, the flat surface 3 and a flat surface that is located on theopposite side from this flat surface 3, is parallel to the flat surface3, and is of a different size from that of the flat surface 3 may beformed on the spherical crystal 2, and the negative electrode 7 may beprovided on this flat surface. These flat surfaces are not essential,however, and can be omitted.

Also, in place of the spherical crystal 2, a spherical crystal may beemployed which has in its interior a spherical core made of aninsulating material, and in which the outer surface of this core iscovered with a semiconductor monocrystal.

2) A ceramic wiring substrate, a metal wiring glass substrate, or asheet composed of a transparent synthetic resin may be employed insteadof the printed substrate in the solar panel 30. Also, the solar cells 1can be electrically connected by wire bonding in the solar panel 30.

3) In the above embodiments, examples of a light-receiving semiconductorapparatus such as a solar ball, solar panel, or solar string weredescribed, but the present invention can be similarly applied to alight-emitting ball, light-emitting panel, light-emitting string, orother such light-emitting semiconductor apparatus. In the case of thislight-emitting semiconductor apparatus, a semiconductor apparatus thatemits light from a ball, a semiconductor apparatus that emits light inplanar fashion from a panel, or a semiconductor apparatus that emitslight from a string can be produced by incorporating a granular lightemitting diode (LED) that emits light through electro-optical conversioninstead of the spherical solar cell 1 discussed above. The sphericallight emitting diode proposed by the inventors of the present inventionin U.S. Pat. No. 6,204,545, or a spherical light emitting diode with asimilar structure, can also be employed as this light emitting diode.

An example of a spherical light emitting diode with a quantum wellstructure will now be described.

The spherical light emitting diode 70 (corresponds to a sphericalsemiconductor device) shown in FIG. 23 comprises a transparent sphericalsapphire 71 (with a diameter of 0.6 to 5.0 mm, for example), a bufferlayer 72 composed of spherical GaN (gallium nitride) formed as a thinfilm on the surface of this spherical sapphire 71, a spherical n typeGaN layer 73 formed as a thin film on the surface of this buffer layer72, a light emitting layer 74 composed of spherical InGaN (indiumgallium nitride) formed as a thin film on the surface of this n type GaNlayer 73, a spherical p type GaN layer 75 formed as a thin film on thesurface of this light emitting layer 74, a pair of electrodes 76, 77(anode 76 and cathode 77), and so forth. The buffer layer 72 and lightemitting layer 74 can be formed on the surface of the spherical sapphire71 by a known process such as MOCVD.

The anode 76 and cathode 77 are provided so as to be aligned in astraight line on either side of the center of the spherical lightemitting diode 70, and are positioned at the two ends of the sphericallight emitting diode 70. The anode 76, which consists of an ohmiccontact, is connected to the p type GaN layer 75, while the cathode 77,which also consists of an ohmic contact, is connected to the n type GaNlayer 73. With this light emitting diode 70, when current flows forwardfrom the anode 76 to the cathode 77, light is generated at a wavelengthcorresponding to the material of the light emitting layer 74 from nearthe pn junction, and radiates to the outside.

When the material forming the light emitting layer 74 is InxGa_(1-x)N,the light is emitted at a longer wavelength as the amount of indium x isincreased. For instance, if x=0.2, blue light with a wavelength λ p of465 nm is emitted, and when x=0.45, green light with a wavelength λ p of520 nm is emitted. A light emitting ball 80 (corresponds to alight-emitting semiconductor apparatus) comprises the spherical lightemitting diode 70, an outer shell member 81 that covers the outside ofthis spherical light emitting diode 70 with a light-transmitting wallcomponent whose thickness is at least ¼ the diameter of the sphericallight emitting diode 70, with the outer surface of this outer shellmember 81 being spherical or partially spherical, a pair of electrodemembers 82, 83 (external leads) connected to the pair of electrodes 76,77 and protruding to outside the outer surface of the outer shell member81. The electrode member 82 is connected to the positive electrode 76 byan electroconductive adhesive, while the electrode member 83 isconnected to the negative electrode 77 by an electroconductive adhesive.The outer shell member 81 is made of a transparent, insulating syntheticresin (such as an epoxy resin). The light generated from the lightemitting layer 74 of the spherical light emitting diode 70 (indicated bythe arrows in the drawings), including the light passing through thespherical sapphire 71, radiates in all directions, as shown in thedrawings. Here, since the light generated by the spherical lightemitting diode 70 radiates from the entire surface of the outer shellmember 81, the light emitting source is larger, the brightness of thelight radiated from this source is decreased, and a softer light isradiated. A diffusion agent (such as glass powder) may be added to theouter shell member 81 for diffusing the light as needed. The lightemitting ball 80 may be used as a single light emitting device, but thespherical light emitting diode 70 or the light emitting ball 80 can alsobe constituted as a light emitting panel such as the solar panels 20,50, 60 discussed above, or can be constituted as a light emitting stringsuch as the solar string 61. In some cases, a reflective film may beprovided to one side of the light emitting ball 80, the light emittingpanel, or the light emitting string so that light is only emitted fromthe side opposite from this side. Also, the spherical light emittingdiode 70 is just one example, and can instead be a light emitting diodethat emits red light, or one that emits white light, or one that emitsany of various other colors of light.

A spherical GaN crystal may be employed instead of the sphericalsapphire 71, in which case the GaN buffer layer 72 can be omitted.

4) The spherical solar cell 1 described above was an example of alight-emitting semiconductor cell produced from a silicon semiconductor,but it can also be made from any other light-receiving semiconductorcell with an photo-electrical conversion function, such as SiGe, GaAsand compounds thereof, InP and compounds thereof, CuInSe2 and compoundsthereof, and CdTe and compounds thereof.

Alternatively, when a light-emitting semiconductor module is made byincorporating light-emitting semiconductor cells, light-emittingsemiconductor cells with an electro-optical conversion function can bemade from semiconductors such as GaAs and compounds thereof, InP andcompounds thereof, GaP and compounds thereof, GaN and compounds thereof,and SiC and compounds thereof.

1. A light-receiving or light-emitting semiconductor apparatus,comprising: at least one spherical semiconductor device with alight-receiving function or a light-emitting function, the sphericalsemiconductor device comprising: a p or n type semiconductor crystalwith a spherical outer shape; a pn junction formed substantiallyspherically on the surface layer of the semiconductor crystal; and apair of electrodes connected to both ends of the pn junction and locatedon either side with interposing the center of curvature or the pnjunction therebetween; an outer shell member covering an outside of thespherical semiconductor device with a light-transmitting wall component,the outer shell member having a thickness of at least ¼ the diameter ofthe spherical semiconductor device so that the outer surface of theouter shell member forms a sherical shape; and the outer shell membercomprising a light-transmitting capsule forming the outer surface of theouter shell member, and a filler comprising a light-transmittingsynthetic resin, said resin being packed into the capsule and cured. 2.A light-receiving or light-emitting semiconductor apparatus, comprising:at least one spherical semiconductor device with a light-receivingfunction or a light-emitting function, the spherical semiconductordevice comprises: a p or n type semiconductor crystal with a sphericalouter shape; a pn junction formed substantially spherically on thesurface layer of the semiconductor crystal; and a pair of electrodesconnected to both ends of the pn junction and located on either sidewith interposing the center of curvature of the pn junctiontherebetween, an outer shell member covering an outside of the sphericalsemiconductor device with a light-transmitting wall component, the outershell member having a thickness of at least ¼ the diameter of thespherical semiconductor device so that the outer surface of the outershell member forms a sphere or partial sphere; and a pair of electrodemembers respectively connected to the pair of electrodes of thespherical semiconductor device and extending through the outer shellmember at least to the outer surface of the outer shell member.
 3. Thesemiconductor apparatus of claim 2, wherein a plurality of microscopiclight scattering surfaces are formed on the outer surface of the outershell member.
 4. The semiconductor apparatus of claim 2, wherein: theouter surface of the outer shell member is a sphere; and the outer shellmember comprises a light-transmitting capsule forming the outer surfaceof the outer shell member, and a filler comprising a light-transmittingsynthetic resin, said resin being packed into the capsule and cured. 5.A light-receiving or light-emitting semiconductor apparatus, comprising:a plurality of spherical semiconductor devices with a light-receivingfunction or a light-emitting function, at least one of the sphericalsemiconductor devices comprising: a p or n type semiconductor crystalwith a spherical outer shape; a pn junction formed substantiallyspherically on the surface layer of the semiconductor crystal; and apair of electrodes connected to both ends of the pn junction and locatedon either side with interposing the center of curvature of the pnjunction therebetween, and an outer shell member covering an outside ofthe at least one spherical semiconductor device with alight-transmitting wall component, the outer shell member having athickness of at least ¼ the diameter of the at least one sphericalsemiconductor device so that the outer surface of the outer shell memberforms a spherical shape said plurality of semiconductor devices beingarrayed in a matrix of a plurality of rows and a plurality of columns; aserial connection mechanism electrically connecting in series theplurality of spherical semiconductor devices in each row or column; anda parallel connection mechanism for electrically connecting in parallelthe plurality of spherical semiconductor devices in each column or row.6. The semiconductor apparatus of claim 5, wherein the outer surface ofthe outer shell member is a sphere; and the outer shell member comprisesa light-transmitting capsule forming the outer surface of the outershell member, and a filler comprising a light-transmitting syntheticresin, said resin being packed into the capsule and cured.
 7. Thesemiconductor apparatus of claim 5, wherein a plurality of microscopiclight scattering surfaces are formed on the outer surface of the outershell member.
 8. A light-receiving or light-emitting semiconductorapparatus, comprising: a plurality of spherical semiconductor deviceswith a light-receiving function or a light-emitting function, at leastone of the plurality of spherical semiconductor devices comprising: a por n type semiconductor crystal with a spherical outer shape; a pnjunction formed substantially spherically on the surface layer of thesemiconductor crystal; and a pair of electrodes connected to both endsof the pn junction and located on either side with interposing thecenter of curvature of the pn junction therebetween, and an outer shellmember covering an outside of the at least one spherical semiconductordevice with a light-transmitting wall component, the outer shell memberhaving a thickness of at least ¼ the diameter of the at least onespherical semiconductor device so that the outer surface of the outershell member forms a sphere or partial sphere; the plurality ofspherical semiconductor devices being arrayed in a matrix of a pluralityof rows and a plurality of columns; a conduction connection mechanismelectrically connecting in parallel the plurality of sphericalsemiconductor devices in each row or column; and the outer shell membercomprising a plurality of substantially spherical outer shell componentscovering respectively the plurality of spherical semiconductor devices,and a flat component formed integrally with the plurality of outer shellcomponents.
 9. The light-receiving or light-emitting semiconductorapparatus according to claim 8, wherein the conduction connectionmechanism comprises a plurality of conductor wires, which are part of anetwork structure constituted by the plurality of conductor wires and aplurality of insulator wires laid out perpendicularly to these conductorwires.
 10. A light-receiving or light-emitting semiconductor apparatuscomprising: a plurality of spherical semiconductor devices including alight-receiving function or a light-emitting function, said plurality ofsemiconductors being disposed in a single column; each of the sphericalsemiconductor devices including a p or an n type semiconductor crystal,said crystal having a spherical outer shape; a pn junction being formedsubstantially spherically on the semiconductor crystal; and a pair ofelectrodes being connected to both ends of the pn junction and beinglocated on either side of the pn junction, the pair of electrodesinterposing a center of curvature of the pn junction therebetween; aconduction connection mechanism electrically connecting in parallel theplurality of spherical semiconductor devices disposed in the singlecolumn; an outer shell member having a cylindrical outer surface andcommonly covering the plurality of spherical semiconductor devices; andsaid outer shell member including a light-transmitting wall component,said wall component having a thickness of at least ¼ the diameter of thespherical semiconductor devices.
 11. A light-receiving or light-emittingsemiconductor apparatus comprising: a plurality of sphericalsemiconductor devices including a light-receiving function or alight-emitting function; the plurality of spherical semiconductordevices being disposed in a plurality of columns; each of the sphericalsemiconductor devices comprising a p or an n type semiconductor crystal,said crystal having a spherical outer shape; a pn junction being formedsubstantially spherically on the semiconductor crystal; a pair ofelectrodes being connected to both ends of the pn junction and beingdisposed on either side of the pn junction, the pair of electrodesinterposing a center of curvature of the pn junction therebetween; aconduction connection mechanism electrically connecting in parallel thespherical semiconductor devices in the columns; an outer shell membercommonly covering the spherical semiconductor devices with alight-transmitting wall component, said wall component having athickness of at least approximately equal to the diameter of thespherical semiconductor devices; and the outer shell member including aplurality of substantially cylindrically shaped members coveringrespectively the columns of spherical semiconductor devices.